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Fossils
Fossils
28
Archaeology
8th Grade
05/16/2010

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Term
Fossil
Definition
Traces or remains of once living organisms
Term
Conditions to form
Definition
1.Usually must have hard parts such as bones,teeth,shells,stem,tree trunks.
2.Must be protected from air and microorganisms.
3.Form in sedimentary rock.
Term
Original Remains
Definition
fossils that are the actual bodies or body parts of organisms.
Term
Ice
Definition
one of the best preservers that preserves prehistoric remains, such a s bones,muscles,skin, ande even hair.
Term
Amber
Definition
a natural sticky substance that preserves the remains of insects and ohter small organisms, resin.{ can harden}
Term
Tar
Definition
a thick, oily liquid
Term
Mold & Cast
Definition
a visible shape tha was left after an animal or plant was buried in seidement and then decayed away, then later becomes filled with minerals.
Term
Petrified Wood
Definition
the stone fossil of a tree
Term
Carbon-Films
Definition
when a dead plant or animal decays, its carbon is left behind as a visible layer.
Term
Trace Fossils
Definition
evidence of an animals presence in a given location such as footprints, traits,animal holes, and even feces.
Term
Tree-rings
Definition
can develop an accurate history of overall weather patterns overtime.
1] thick rings{ lots of rainfall
2] thin rings{dry years,period}
Term
ice cores
Definition
a tubalar sample that shows the layers of snow and ice that have built over thousand of years.
- help understand how Earht's climate is changing and how it can change to the future.
Term
Relative Age
Definition
is the age of an event in object in relation to other events or objects.
Term
Law of Superpostition
Definition
states tha in horizontal layers of undisturberbed sedimentary rock, the oldest rock layers are on the bottom and the youngest are on the top.
Term
intrusion
Definition
when magam pushes its way through the rock layers and hardens into igneous rock, always younger than the rock surrounding it.
Term
unconformity
Definition
a gap in rock layerr, oftem cause by erosion.
Term
index fossil
Definition
tell the relative ages of rock layers in which they are found.
1] only lives for certain period
2]were abudunt
3]were widespread
Term
absoulute age
Definition
is the actual number of years since the rock formed or the evetn occures{used on igneous rock}
Term
radioactive dating
Definition
is the process of measuring the rate of change of a raioactive
- such as carbon -14 & uranium 235 into its daughter elements.
Term
Half-life
Definition
is the time it takes for half of the atoms of radioactive sample to decay{ change from unstable to another form}
Term
uniformitarism
Definition
A] earth is always-changing place
B] the same forces of change at work today were at work in the past{ mountain-building,erosion.etc}
Term
How old is earth?
Definition
4.6 billion years old
Term
geologic time scale
Definition
divides the history of the earth inot sections of time based upon major biologic and geologic changes.
Term
Eons,Eras,Periods,Epochs
Definition
Eons-thelargest unit of time is broken into eras,eras into periods,periods into epochs}
Term
mass extinction
Definition
one of the several periods in Earth's history when large numbers of spiecies becames extinct at nearly the same time.
Term
evoulution
Definition
the process through which species change over time; can refer to the changes in a particular population or to the formation and extinction of spiecies over the course of Earth's history.
Term
natural selection
Definition
the process through which apiecies thgat are best suited to their enviroment survive and reproduce at a higher rate than other members of the spiecies.
Term
speciation
Definition
the evoulution of a new species from an exsisting species.
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